They don't lack the density, they just shifted how these needs are met. In Europe, you can have a teensy town of 2000 people and a cafe and bar and all your shops in walking distance still. In the U.S., this used to be the case until the 1950s or so, when automobiles made it possible to develop larger, regional stores that service a number of towns for all their needs and could dominate over the competition (Walmart today is what used to be a dozen separate services in one hulking brick and mortar).
